Blow-molded plastic boxes of double-wall construction are widely used where economy, durability and light weight are desired. The light weight reduces shipping costs, and the double-wall construction provides cushioning against shocks. Such boxes may have molded integral snap-type latches as in U.S. Pat. No. 3,536,435 (Schurman et al.) and U.S. Pat No. 3,659,999 (Schurman). As noted in U.S. Pat. No. 3,933,381 (Schurman), such latches have been deficient in strength and durability and are particularly vulnerable to opening under accidental jarring impact.
The latter patent deals with this problem by employing a sliding metal bolt which is formed from a wire. A loop in the wire acts as handle and as a detent means, snapping into locked position behind a protuberance 42 as seen in FIG. 4. While this bolt-type latch provides much more secure latching, it involves the extra cost of drilling out the ends of the groove which carries the bolt. In actual use, the loop has sometimes been accidentally knocked out of its detented position, and further jarring has allowed the bolt to move to the open position, thus spilling the contents of the box.